1. Field of the Invention
The present invention relates to a disposable dispensing cartridge of the type adapted to be releasably received in a hand-held applicator having a movable plunger.
2. Description of the Related Art
A number of hand-held dispensing devices are available for dispensing various types of materials. In many instances, the dispensing device is an assembly that includes a reusable dispenser or applicator and a disposable cartridge. The cartridge contains a quantity of a composition or material to be dispensed and is releasably received in a receptacle of the applicator.
In some dispensing assemblies that include an applicator and a cartridge, the applicator has a plunger that is advanced by the user during a dispensing operation. Often, the plunger is received in an open end of the cartridge and bears against a piston within the cartridge. As the plunger is advanced to move the piston, the piston expels a quantity of material through a front outlet opening of the cartridge.
Dispensing devices that include a reusable applicator and a disposable cartridge are favored in many instances, especially in instances where the applicator is relatively expensive in comparison to the cost of the cartridge. For example, many applicators have a movable lever or arm for facilitating advancement of the plunger. Some applicators have a ratchet mechanism associated with the arm or lever for enhancing control over movement of the plunger. Obviously, it is desirable to reuse such applicators in order to reduce costs and avoid disposal issues.
Dispensing devices with disposable cartridges are often used in the field of dentistry for dispensing dental compositions such as restoratives, adhesives, cements, etching gels, sealants and the like. In some instances, the cartridge and the front portion of the applicator receiving the cartridge are relatively small so that the cartridge can be readily maneuvered in the oral cavity during a dispensing operation. In that manner, the dental material contained in the cartridge may be conveniently dispensed directly onto the tooth structure as needed.
Examples of hand-held applicators (also called dispenser or ejector-type guns) that have been used in dentistry are described in U.S. Pat. Nos. 4,198,756, 4,391,590 and 4,472,141. Examples of cartridges (also known as capsules) useful with those applicators are described, for example, in U.S. Pat. Nos. 4,391,590, 4,767,326, 5,100,320 and 5,624,260.
In the field of dentistry, dispensing cartridges are often relatively small and adapted to be used with a single patient. The cartridge is disposed of after the procedure has been accomplished and the applicator is disinfected before use with a subsequent patient. In this manner, the risk of transferring an infectious disease from one patient to another is substantially reduced.
However, many of the dental applicators and disposable cartridges that are presently commercially available are not satisfactory for use in dispensing paste-like compositions having a relatively high viscosity. In such instances, the user must apply a relatively high force to the lever of the applicator in order to eject the composition from the cartridge. As can be appreciated, precise control over placement of the discharged composition in the oral cavity can be hindered whenever the user must exert an undue effort to expel the composition from the cartridge.
As a result, dental practitioners in the past have often used a spatula or other similar tool for placing high viscosity paste-like compositions (such as restorative materials) in the oral cavity. This practice involves placing a small quantity of the material onto the spatula and then maneuvering the spatula as needed to place and transfer the material onto the patient's tooth structure. As can be appreciated, such practice is somewhat time consuming and not as convenient as dispensing methods that involve dispensing dental compositions from a cartridge directly onto the tooth structure.
In some instances, syringes having a plunger that is advanced by a thumb screw have been used to dispense viscous dental compositions. The thumb screw provides a substantial mechanical advantage so that relatively viscous compositions can be dispensed without undue effort. However, such dispensing typically involves the use of both hands of the practitioner, one hand being used to hold the body of the syringe while the other hand is used to turn the thumb screw. Moreover, such devices are generally not used to dispense a composition directly to a patient's tooth structure.
As such, there is a need in the art for a cartridge especially adapted for use for one-handed dispensing of high viscosity compositions. Preferably, such a cartridge could be used with commercially available applicators so that a specially-made applicator is unnecessary. Moreover, there is a need in the art to provide a dispensing cartridge for use with high viscosity compositions that is especially suitable for use by dental practitioners in order to dispense a precise quantity of such compositions directly onto a tooth surface and at an exact location as desired without undue effort.